The present invention relates to techniques for performing signal processing on audio signals, and more particularly to graphical audio signal control.
In the field of stereo audio signal processing, a technique has heretofore been developed which is capable of displaying sound image positions on a frequency-band-by-frequency-band basis, as disclosed for example in Japanese Patent No. 3912386. With such a technique, it is possible to know in detail sound image positions of sounds represented by stereo audio signals.
When level adjustment of audio signals is to be performed on the frequency-band-by-frequency-band basis, graphic equalizers etc. are employed. However, although the use of the graphic equalizer can adjust level adjustment frequency band by frequency band, all of sound signal levels in a particular frequency band would be adjusted, and thus, it is not possible to adjust a level of a sound having a particular sound image position.
Further, among the graphic equalizers are ones capable of performing level adjustment independently for individual ones of stereo left (L) and right (R) channels. However, even with such a graphic equalizer, when a signal level of only the L channel has been lowered for a particular frequency band, a signal level of the R channel would rise relatively for that particular frequency band, so that the sound image position would move as a whole to the R channel side. Thus, even with the graphic equalizer, a sound having a particular sound image position could not be adjusted in level.